bug: not scaling up from 0 replicas using hpa (#544)

* bug: not scaling up from 0 replicas using hpa

* clean up logic a bit

pkg/resourcegenerator/deployment/deployment_test.go

@@ -1,9 +1,12 @@
 package deployment
 
 import (
+	"github.com/kartverket/skiperator/api/v1alpha1"
 	"github.com/kartverket/skiperator/pkg/testutil"
+	"github.com/kartverket/skiperator/pkg/util"
 	"github.com/stretchr/testify/assert"
 	appsv1 "k8s.io/api/apps/v1"
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"testing"
 )
 
@@ -21,3 +24,16 @@ func TestDeploymentMinimalAppShouldHaveLabels(t *testing.T) {
 	assert.Equal(t, appLabel["app"], depl.Spec.Selector.MatchLabels["app"])
 	assert.Equal(t, appLabel["app"], depl.Spec.Template.Labels["app"])
 }
+
+func TestHPAReplicasIsZero(t *testing.T) {
+	// Setup
+	r := testutil.GetTestMinimalAppReconciliation()
+	r.GetSKIPObject().(*v1alpha1.Application).Spec.Replicas = &apiextensionsv1.JSON{Raw: []byte(`{"min": 0, "max": 0, "targetCpuUtilization": 200}`)}
+	// Test
+	err := Generate(r)
+
+	// Assert
+	assert.Nil(t, err)
+	depl := r.GetResources()[0].(*appsv1.Deployment)
+	assert.Equal(t, depl.Spec.Replicas, util.PointTo(int32(0)))
+}

pkg/resourceprocessor/resource.go

@@ -33,8 +33,16 @@ func preparePatch(new client.Object, old client.Object) {
 	case *v1.Deployment:
 		deployment := old.(*v1.Deployment)
 		definition := new.(*v1.Deployment)
+
+		// Handling HPA.
+		// If the replicas field is not set in the definition, we should set it to 1 if the deployment has 0 replicas or HPA will not work.
+		// If the replicas field is set in the definition, we should use that value so we don't scale down.
 		if definition.Spec.Replicas == nil {
 			definition.Spec.Replicas = deployment.Spec.Replicas
+
+			if *deployment.Spec.Replicas == int32(0) {
+				definition.Spec.Replicas = util.PointTo(int32(1))
+			}
 		}
 		// The command "kubectl rollout restart" puts an annotation on the deployment template in order to track
 		// rollouts of different replicasets. This annotation must not trigger a new reconcile, and a quick and easy

tests/application/hpa/chainsaw-test.yaml

@@ -31,5 +31,8 @@ spec:
             file: patch-application-set-0-assert.yaml
         - error:
             file: patch-application-set-0-error.yaml
-
-
+    - try:
+        - apply:
+            file: patch-application-scale-up-from-0.yaml
+        - assert:
+            file: patch-application-scale-up-from-0-assert.yaml

tests/application/hpa/patch-application-scale-up-from-0-assert.yaml

@@ -0,0 +1,27 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test-deployment-hpa
+spec:
+  replicas: 2
+
+---
+apiVersion: autoscaling/v2
+kind: HorizontalPodAutoscaler
+metadata:
+  name: test-deployment-hpa
+spec:
+  minReplicas: 2
+  maxReplicas: 4
+  metrics:
+    - resource:
+        name: cpu
+        target:
+          averageUtilization: 200
+          type: Utilization
+      type: Resource
+  scaleTargetRef:
+    kind: Deployment
+    apiVersion: apps/v1
+    name: test-deployment-hpa
+

tests/application/hpa/patch-application-scale-up-from-0.yaml

@@ -0,0 +1,11 @@
+apiVersion: skiperator.kartverket.no/v1alpha1
+kind: Application
+metadata:
+  name: test-deployment-hpa
+spec:
+  image: image
+  port: 8080
+  replicas:
+    min: 2
+    max: 4
+    targetCpuUtilization: 200